An unusual case associating ileal Crohn's disease and diffuse large B-cell lymphoma of an adjacent mesenteric lymph node.

Intestinal non-Hodgkin's lymphomas are a rare complication of long-standing Crohn's disease and generally arise in sites of active inflammatory disease. To our knowledge, we report the first case of an unusual association between ileal Crohn's disease and a diffuse large B-cell non-Hodgkin's lymphoma involving an adjacent mesenteric lymph node but not the intestinal tract. A 22-year-old man was seen for intermittent abdominal pain, vomiting, and severe weight loss that were suggestive of intestinal obstruction. A segmental ileocolonic resection was performed. Gross examination revealed a terminal ileal inflammatory stenosis and enlarged mesenteric lymph nodes. Histologically, terminal ileal Crohn's disease was associated with a diffuse large cell lymphoma localized within one mesenteric lymph node without intestinal involvement. Immunophenotyping performed on deparaffinized sections demonstrated the B phenotype of this lymphoma.